Ramalina

Ramalina is a genus of fruticose lichens that often colonize the bark of fruit and ornamental trees. From an agronomic perspective, it is classified as an epiphyte, meaning it uses the tree as a physical support rather than a nutrient source. While it does not directly consume plant sap, its presence is a biological indicator of tree vigor and environmental conditions.

The primary hosts for Ramalina are mature or aging fruit trees such as apples, pears, and stone fruits. These trees possess rough, cracked bark that provides an ideal substrate for the lichen to attach. It is rarely found on young, rapidly growing trees, as the constant expansion of the bark surface makes it difficult for the lichen to maintain its hold.

Symptoms are easily identified by the appearance of grey-green, shrub-like, or hanging thalli attached to the bark. These growths can spread over large portions of the trunk and primary branches if left unchecked. Over time, the area covered by the lichen becomes a haven for moisture, which can lead to premature bark decay and inhibit normal gas exchange in the tree trunk.

Development and spread are driven by high humidity, poor air circulation, and insufficient sunlight. Gardens with dense, unpruned canopies are particularly susceptible to colonization. Ramalina thrives in environments where the bark remains damp for long periods, which often occurs in neglected orchards with poor light exposure and low maintenance standards.

The harmfulness of Ramalina lies in its ability to serve as a shelter for overwintering pests, such as scales and mites, and as a reservoir for pathogenic fungal spores. To protect orchards, growers should implement regular sanitary pruning to improve airflow. Mechanical cleaning of the bark using specialized scrapers is the most effective removal method, followed by applications of copper or iron-based solutions to sanitize the bark surface.